class Solution516 {
    public int longestPalindromeSubseq(String s) {
        int n = s.length() ;
        char[] arr = s.toCharArray() ;
        int[][] dp = new int[n][n] ;
        for(int i=n-1 ; i >= 0  ; i --){
            for(int j=i ; j < n ; j ++){
                if(arr[i] == arr[j]){
                    if(i == j){
                        dp[i][j] = 1 ;
                    }else if(i + 1 == j){
                        dp[i][j] = 2 ;
                    }else{
                        dp[i][j] = dp[i+1][j-1] + 2 ;
                    }
                }else{
                    dp[i][j] = Math.max(dp[i+1][j] , dp[i][j-1]) ;
                }
            }
        }

        return dp[0][n-1] ;
    }
}